Seat portion of a seat

ABSTRACT

A seat portion ( 4 ) for a seat ( 2 ), which seat portion ( 4 ) comprises at least a first part ( 8 ) which is made of a first plastics foam material of a first density, and a second part ( 10 ) which is made of a second plastics foam material of a second and different density.

This invention relates to a seat portion of a seat, and also to a seatwhen provided with the seat portion.

There are may different types of seats comprising a seat portion and abackrest portion. The seats are often such that the seat portion is notcomfortable to sit on, and does not give adequate support to theposterior of a person sitting on the seat portion. The seat portion may,for example, restrict the positioning of the person's pelvic girdle, andit may apply undue pressure to the person's ischial tuberosities. Inaddition, in the region of the person's posterior, the seat portion maycause restriction of local blood flow and/or pinching of local nerves.

It is an aim of the present invention to reduce the above mentionedproblem.

Accordingly, in one non-limiting embodiment of the present inventionthere is provided a seat portion for a seat, which seat portioncomprises at least a first part which is made of a first plastics foammaterial of a first density, and a second part which is made of a secondplastics foam material of a second and different density.

The seat portion of the present invention is able to give a good degreeof comfort to a person sitting on the seat portion, irrespective of theseat portion being used at different times by different persons ofdifferent heights and weights.

The seat portion may be one in which the second part is in the form ofan insert which fits into a complementarily shaped recess in the firstpart.

The insert may comprise a pair of pads which are positioned so as to beunderneath the cheeks of the posterior of a person sitting on the seatportion, and a pair of legs which are positioned so as to be underneaththe thighs of the person sitting on the insert. If desired, the pads andthe legs may have curved faces which engage complementarily curved facesin the recess. Alternatively, if desired, the pads and the legs may haverectilinear faces which engage rectilinear faces in the recess.

The seat portion is preferably one in which the second density is alesser density than the first density, whereby the second part is softerthan the first part.

The seat portion may be one in which the second part does not have anyvoids of the type used to increase flexibility and/or save plastics foammaterial.

As an alternative to the second part being in the form of an insert, thesecond part may be in the form of a surface-mounted addition which restson an upper surface of the first part.

In all embodiments of the invention, the second part may be fixed to thefirst part. The fixing may be effected by an adhesive, stitching or anyother suitable and appropriate fixing means. Alternatively, the secondpart may be movable with respect to the first part.

The seat portion may be formed only of the first and second parts.Alternatively more parts may be employed so that, for example, the seatportion may comprise the first and second parts and also one, two orthree more parts.

The seat portion may include a heating element.

As indicated above, the present invention also extends to a seat whenincluding the seat portion of the invention.

The seat may include a backrest portion.

The backrest portion may comprise a main part which is made of aplastics foam material of the first density, and a support part which ismade of a plastics foam material of a second and different density. Withsuch a backrest portion, the seat may be such that a person sifting onthe seat portion and resting their back on the backrest portion is ableto obtain optimum lumbar support for the back of the person,irrespective of the height and weight of the person. Usually thebackrest portion will comprise only one support part. If desired howeverthe backrest portion may comprise more than one support part.

The support part may be fixed to the main part. The fixing may beeffected by an adhesive, stitching or any other suitable and appropriatefixing means. Alternatively, the support part may be movable withrespect to the main part. With a support part which is movable withrespect to the main part, a person sitting on the seat and resting theirback on the support part is able to cause the support part to adjust itsposition with respect to the main part in order to obtain optimum lumbarsupport.

The main part of the backrest portion may be such that it increases inthickness in a direction towards the seat portion.

The support part of the backrest portion may be a rectilinear supportpart. Other shapes for the support part may be employed. The rectilinearsupport part may be conical in shape, with longest sides extendingtowards the seat portion.

In the backrest portion, the plastics foam material of the first densitymay be harder than the plastics foam material of the second density, inwhich case the main part will be harder than the support part. Thereverse arrangement may be employed in which case the plastics foammaterial of the first density will be softer than the plastics foammaterial of the second density, whereby the main part will be softerthan the support part.

The seat may include a peripheral frame which extends around theperiphery of the backrest portion.

The seat may include a headrest portion.

The seat may be any suitable and appropriate seat. Thus, for example,the seat may be a vehicle seat for a motor vehicle, an aircraft seat foran aircraft, a boat seat for a boat, a military seat for a militaryvehicle, a train seat for a train, a hovercraft seat for a hovercraft, adomestic seat for domestic use, an office seat for office use, or anindustrial seat for use in industrial premises.

Where the seat is a vehicle seat for a motor vehicle, then the vehiclemay be any suitable and appropriate vehicle including a car, van, bus,coach or lorry. Where the seat is a seat for a boat or a hovercraft,then the seat may be especially advantageous for ferries wherepassengers are generally required to sit together in their seats for theduration of their journey. Where the seat is a domestic seat, then thedomestic seat may be a chair, armchair or settee.

The seat may be such that the seat portion and/or the backrest portionare made of a wide variety of different plastics foam materials. Varioussuitable numbers of different pieces of plastics foam material may beemployed.

In one embodiment of the invention the seat portion may comprise firstpart made of a first plastics foam material of a first hardness and asecond part which is made of a second plastics foam material of a secondhardness less than the first hardness, wherein the second part isattached to an upper surface of the first part so that in usecompressive forces applied to the second part are transmitted to anddistributed through the first part which thus acts to limit compressivedeformation of the second part. Such a seat portion is especially usefulfor seating in a mobile environment. An under surface of the second partmay have protuberances, and the upper surface of the first part may haverecesses complementary in shape to the protuberances. An upper surfaceof the second part may be substantially planar, and co-planar with thesurrounding non-recessed area of the first part.

Embodiments of the invention will now be described solely by way ofexample and with reference to the accompanying drawings in which:

FIG. 1 shows a first seat of the present invention;

FIG. 2 shows part of the seat shown in FIG. 1;

FIG. 3 shows a second seat of the invention;

FIG. 4 shows a third seat of the invention;

FIG. 5 is a section through the seat shown in FIG. 4;

FIG. 6 shows a seat portion of a seat;

FIG. 7 shows a backrest portion of a seat;

FIG. 8 is an exploded view of the backrest portion shown in FIG. 7;

FIG. 9 shows a headrest for a seat;

FIGS. 10-14 show different seat portions of the invention; and

FIGS. 15-20 show different backrest portions that may be used in seatsof the present invention.

Referring to FIGS. 1 and 2, there is shown a seat 2 comprising a seatportion 4 and a backrest portion 6. The seat portion 4 comprises a firstpart 8 which is made of a first plastics foam material of a firstdensity. The seat portion 4 also comprises a second part 10 which ismade of a second plastics foam material of a second and differentdensity.

The second part 10 is in the form of an insert which fits into acomplementarily shaped recess 12 in the first part 8. The second part 10in the form of the insert comprises a pair of pads 14, 16 which are sopositioned as to be underneath the cheeks of the posterior of a person(not shown) sifting on the seat portion 4. The second part 10 in theform of the insert also comprises a pair of legs 18, 20 which arepositioned so as to be underneath the thighs of the person sitting onthe insert. As can be appreciated from FIGS. 1 and 2, the pads 14, 16and the legs 18, 20 have curved faces 22. These curved faces 22 engagecomplementarily curved faces 24 in the recess 12.

The seat portion 4 is such that the second density is a lesser densitythan the first density, whereby the second part 10 is softer than thefirst part 8. The second part 10 does not have any voids of the typeused to increase flexibility and/or save plastics foam material.

The second part 10 is fixed in the first part 8 by fixing means in theform of an adhesive (not shown).

The backrest portion 6 comprises a main part 26 which is made of aplastics foam material of a first density, and a support part 28 whichis made of a plastics foam material of a second and different density. Aperson sitting on the seat 2 and resting their back on the supportportion 28 is able to obtain optimum lumbar support for the back of theperson irrespective of the height and weight of the person. The supportpart 28 is fixed to the main part 26 by fixing means in the form of anadhesive (not shown).

As can be seen from FIGS. 1 and 2, the main part 26 is such that itincreases in thickness in a direction towards the seat portion 4. Thesupport part 28 is a rectilinear support part 28. The rectilinearsupport part 28 is conical shape with longest sides 30 extending towardsthe seat portion 4.

In the backrest portion 6, the plastics foam material of the firstdensity of the main part is harder than the plastics foam material ofthe second density of the support part.

The seat 2 includes a peripheral frame (not shown). which extends aroundthe periphery of the backrest portion 6.

Referring now to FIG. 3, there is shown a seat 36. Similar parts as inFIGS. 1 and 2 have been given the same reference numerals for ease ofcomparison and understanding. From a comparison of the seats 2 and 36,it will be seen that the seat portions 4 in the seats 2 and 36 are verysimilar. The spaced-apart legs 18, 20 in both seat portions 4 help tokeep the person's legs slightly apart for maximum comfort duringsitting.

In FIG. 3, the seat 36 is such that the backrest portion 6 comprises alower part 38 and an upper part 40. The upper part 40 is larger than thelower part 38 as shown. Both the lower part 38 and the upper part 40contain portions of the support part 28 as shown.

The upper part 40 has a horizontal slot 42 for enabling a headrestportion 44 to be mounted on the backrest portion 6.

The seats 2, 36 are suitable for forming aircraft seats.

Referring now to FIGS. 4 and 5, there is shown a seat 46 which issuitable for forming a train seat. In the seat 46, similar parts as inthe seats 2 and 36 have been given the same reference numerals for easeof comparison and understanding. In the seat 46, it will be seen thatthere is no separate headrest portion. It will also be seen that thesupport part 28 is basically parallel-sided rather than being conical asshown in FIGS. 1, 2 and 3. The seat 46 is mounted on a panel support 48which is itself fixed with respect to an upright pole 50. The pole 50has a footplate 52 for enabling the pole 50 to be secured to a floor ina train. FIG. 5 illustrates how the seat 46 has a peripheral tubularframe 54.

FIG. 6 shows in exploded form a seat portion 58. For ease of comparisonand understanding, similar parts as in the seat portion 4 have beengiven the same reference numerals. In the seat portion 58, the secondpart 10 will usually be stuck to the first part 8. Other fixing meanssuch for example as sewing may be employed. Alternatively, the secondpart 10 may move with a sliding action with respect to the first part 8.

In the aircraft seats 2 and 36 of FIGS. 1 to 3, the under surface insert10 is secured, e.g. by adhesive, to the recessed upper surface of thesupport part 8, in the manner illustrated in FIG. 6 which shows apreferred construction for the seat portion of the seats of FIG. 1 to 3.It can be seen from FIG. 6 that the upper surface of the insert 10 issubstantially planar and, when attached to the part 8, is co-planar withthe non-recessed areas of the upper surface of the part 8.

When the seat 2 or 36 is occupied, the compressive force applied to theinsert 10 is transmitted to and distributed to the support part 8 whichin turn transmits the force to the seat frame (not shown) whichtypically comprises an aluminium alloy panel supporting the undersurface of the part 8. Thus, the insert 10 is supported by the part 8which acts to prevent excessive compressive deformation of the insert10. As a consequence, the seat does not have hard points and does notsuffer from “bottoming out” and is thus comfortable for occupantsthroughout a wide range of body weights.

The deformability of the foam materials has been expressed in terms oftheir densities. In the case of seats for aircraft, the parameter usedto define deformability is hardness, expressed in Newtons, i.e. theforce to compress the foam material by a unit distance. For the aircraftseats of the FIGS. 1 to 3, the insert 10 will always have a hardnesslower than that of the support part 8. Preferred hardness ranges are50-175 Newtons for the insert 10, 200-400 Newtons for the support part8, 125-175 Newtons for the main part 26, and 50-125 Newtons for thesupport part 28.

FIGS. 7 and 8 show a backrest portion 60. Similar parts as in thebackrest portion 6 have been given the same reference numerals for easeof comparison and understanding. In the backrest portion 60, it will beseen that the main part 26 and the support part 28 are differentlyshaped to the main part 26 and the support part 28 in the backrestportion 6. FIG. 8 shows how the backrest portion 60 with its outwardlysloping longest sides 30 fits into a complementarily shaped recess 62 inthe main part 26 of the backrest portion 60. The support part 28 may befixed in position in the recess 62 by fixing means such for example asan adhesive or stitching. Alternatively, the support part 28 may bemovable in the recess 62 with respect to the main part 26.

FIG. 9 shows a headrest portion 64 which may fit to the backrest portionof a seat. The headrest portion 64 is shaped as shown and it has a mainpart 66 and a head support part 68. The head support part 68 is of adifferent density to the main part 66. The head support part 68 willusually be softer than the main part 66 but it may be harder if desired.The head support part 68 may move with respect to the main part 66. Themovement will normally be a sliding movement with the head support part68 sliding in a complementarily shaped recess in the main part 66.

FIGS. 10-14 show different types of seat portions. Similar parts as inthe seat portion 4 have been given the same reference numerals for easeof comparison and understanding.

FIG. 10 shows the seat portion 70 having a first part 8 and a secondpart 10. The first part 8 has a shaped recess 12 which is generallysimilar to the shaped recess 12 shown in the seat portion 4. The secondpart 10 is generally similar to the second part 10 shown in the seatportion 4. In FIG. 10, it will be noted that the first part 8 has stylelines 72, whilst the second part 10 has style lines 74.

In FIG. 11, there is shown a seat portion 76 in which the legs 18, 20are each in two parts 18 a, 18 b, and 20 a and 20 b. Similarly, the seatportion 8 is in two parts 8 a, 8 b.

FIG. 12 shows a seat portion 78 in which the first part 8 and the secondpart 10 are similar to the first part 8 and the second part 10 shown inFIG. 10, but without the style lines 74.

FIG. 13 shows a seat portion 80 which is similar to the seat portion 78,except that the first part 10 is formed in three pieces with a mainpiece 10 a, and two insert pieces 10 b, 10 c which insert intocorrespondingly shaped recesses 82, 84.

FIG. 14 shows a seat portion 86 having a first part 8 and a second part10. The first part 8 is too thin to be provided with a shaped recesssuch as a recess 12. In view of this, the second part 10 is in the formof a surface-mounted addition which is stuck or otherwise secured bysuitable fixing means in position on top of the first part 8, as shownby broken lines on the first part 8.

FIG. 15 shows a backrest portion 88 having a main part 26 and a supportpart 28. The support part 28 is shaped as shown and it fits into acomplementarily shaped recess 90. The main part 26 and the support part28 are made of plastics foam material of different densities. Theplastics foam material of the main part 26 may be of a first and harderdensity than the plastics foam material of the second part 28. Thereverse arrangement may however be employed if desired.

FIG. 16 shows a backrest portion 92 which is like the backrest portion88 except that the support part 28 is slightly differently shaped, as isthe complementarily shaped recess 90.

FIG. 17 shows a backrest portion 94 which does not have a back supportpart 28. However the main part 26 has a recess 96 for receiving aheadrest portion 98. The headrest portion 98 may be fixed or movable inthe recess 96.

FIG. 18 show a backrest portion 100 in which the main part 26 is in twoparts 26 a, 26 b. Also, the support part 28 is in two parts 28 a, 28 b.All the parts split about a split line 102.

FIG. 19 shows a backrest portion 104 is which the support part 28 istriangularly shaped in cross section. The support part 29 fits into acorresponding triangularly shaped recess 106 in the main part 26.

FIG. 20 shows a backrest portion 108 which is like the backrest portion104 except that the main part 26 and the support part 28 are providedwith style lines 110, 112.

It is to be appreciated that the embodiments of the invention describedabove with reference to the accompanying drawings have been given by wayof example only and that modifications may be effected. Thus, forexample, a wide variety of different types of plastics foam materialsmay be employed in the seat portions 4 and the backrest portions 6.Also, all of the seats of the present invention may be covered with anappropriate fabric covering. The seats may be of different designs tothose shown. The seat portions shown in the drawings may each include aheating element if desired, for example if the seats are to be forinstallation in road vehicles.

1. A seat portion for a seat, which seat portion comprises at least afirst part which is made of a first plastics foam material of a firstdensity, and a second part which is made of a second plastics foammaterial of a second and different density.
 2. A seat portion accordingto claim 1 in which the second part is in the form of an insert whichfits into a complementarily shaped recess in the first part.
 3. A seatportion according to claim 2 in which the insert comprises a pair ofpads which are positioned so as to be underneath of the posterior of aperson sitting on the seat portion, and a pair of legs which arepositioned so as to be underneath the thighs of the person sitting onthe insert.
 4. A seat portion according to claim 3 in which the pads andthe legs have curved faces which engage complementarily curved faces inthe recess.
 5. A seat portion according to claim 1 in which the seconddensity is a lesser density than the first density, whereby the secondpart is softer than the first part.
 6. A seat portion according to claim1 in which the second part does not have any voids of the type used toincrease flexibility and/or save plastics foam material.
 7. A seatportion according to claim 1 in which the second part is in the form ofa surface-mounted addition which rests on an upper surface of the firstpart.
 8. A seat portion according to claim 1 in which the second part isfixed to the first part.
 9. A seat portion according to claim 1 in whichthe second part is moveable with respect to the first part.
 10. A seatportion according to claim 1 and including a heating element.
 11. A seatwhen including a seat portion according to claim
 1. 12. A seat accordingto claim 11 and including a backrest portion.
 13. A seat according toclaim 12 in which the backrest portion comprises a main part which ismade of a plastics foam material of a first density, and a support partwhich is made of a plastics foam material of a second and differentdensity.
 14. A seat according to claim 13 in which the support part isfixed to the main part.
 15. A seat according to claim 13 in which thesupport part is moveable with respect to the main part.
 16. A seataccording to claim 13 in which the main part is such that it increasesin thickness in a direction towards the seat portion.
 17. A seataccording to claim 13 in which the support part is a rectilinear supportpart.
 18. A seat according to claim 17 in which the rectilinear supportpart is conical in shape with longest sides extending towards the seatportion.
 19. A seat according to claim 13 in which the backrest portionis such that the plastics foam material of the first density is harderthan the plastics foam material of the second density.
 20. A seataccording to claim 12 and including a peripheral frame which extendsaround the periphery of the backrest portion.
 21. A seat according toclaim 12 and including a headrest portion.
 22. A seat portion for aseat, which seat portion comprising a first part made of a firstplastics foam material of a first hardness and a second part which ismade of a second plastics foam material of a second hardness less thanthe first hardness, wherein the second part is attached to an uppersurface of the first part so that in use compressive forces applied tothe second part are transmitted to and distributed through the firstpart which thus acts to limit compressive deformation of the secondpart.
 23. A seat portion according to claim 22 in which an under surfaceof the second part has protuberances, and the upper surface of the firstpart has recesses complementary in shape to the protuberances.
 24. Aseat portion according to claim 23 in which an upper surface of thesecond part is substantially planar, and co-planar with the surroundingnon-recessed area of the first part.